<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        
        body {
            background: url(images/1.jpg) no-repeat center top;
        }
        
        li {
            list-style: none;
        }
        
        .baidu {
            overflow: hidden;
            margin: 100px auto;
            background-color: #fff;
            width: 410px;
            padding-top: 3px;
        }
        
        .baidu li {
            float: left;
            margin: 0 1px;
            cursor: pointer;
        }
        
        .baidu img {
            width: 100px;
        }
    </style>
</head>

<body>
    <ul class="baidu">
        <li><img src="images/1.jpg"></li>
        <li><img src="images/2.jpg"></li>
        <li><img src="images/3.jpg"></li>
        <li><img src="images/4.jpg"></li>
    </ul>
	<script type="text/javascript">
		//获取元素对象集合
		var imgs = document.querySelector('.baidu').querySelectorAll('img');
		console.log(imgs);//NodeList length-4
		//循环
		for(var i=0;i<imgs.length;i++){
			//给每个小图绑定点击事件
			//imgs[i] == document.querySelector('.baidu').querySelectorAll('img')[0];
			imgs[i].onclick = function(){
				//this就是imgs[i]元素对象
				//设置特殊元素的背景图片
				console.log(this.src);
				document.body.style.background = 'url('+this.src+') no-repeat center top';
			}
		}
	</script>
</body>

</html>
